1. Field of the Invention.
This invention relates generally to weaving loom mechanisms and relates particularly to apparatus for moving a weft thread carrying mechanism through the shed of a multiplicity of warp threads.
2. Description of the Prior Art.
Heretofore, in substantially all power operated weaving looms, a multiplicity of warp threads have been provided which extend from front to rear of the loom and normally such warp threads extend through harnesses on which is mounted a heddle for each of the warp threads. The harnesses are independently movable so that the heddles of certain of the warp threads are in raised position and the heddles of the other warp threads are in a lowered position with the angle between the upper and lower threads defining the shed of the cloth being woven. A loom lay is provided having a raceway and a reed or comb and such lay normally is carried by a pair of swingably mounted swords. The opposite ends of the lay usually include a shuttle box and such boxes receive and declerate a shuttle or missle which is thrown from one end of the lay to the other.
The shuttle or missile either carries or is connected to a weft thread or filler so that when the shuttle or missile is thrown along the raceway of the lay, the weft thread is placed in the shed of the warp threads. When the weft thread is in place, the lay is swung toward the front of the loom to cause the reed to beat up the weft thread after which the lay is retracted to an inoperative position and at least some of the heddles which have been in a raised position are lowered and at least some of the heddles which have been in a lowered position are raised. After the heddles have been operated, the shuttle or missile is operated to place another weft thread in the shed of the warp thread and the beat-up operation is repeated.
Most shuttles of fly shuttle looms are driven by a picker stick having a pick head at one end for engaging the end of the shuttle and the opposite end of such picker stick normally is mounted on a foot mechanism located at the base of the swords which permits swinging movement of the picker stick in multiple directions. A check strap ordinarily engages the picker stick adjacent to the lay and a lug strap normally engages the picker stick intermediate the lay and the foot mechanism. In order to drive the picker stick to cause the shuttle to be propelled from one end of the lay to the other, the lug strap is swingably connected to an oscillating shaft the opposite ends of which are journaled in bearings carried by the frame of the loom. A cam follower is rotatably mounted on a follower arm which is fixed to the oscillating shaft and such cam follower normally engages a cam driven from a power plant on the loom.
Usually the cam has a relatively short toe portion which extends for approximately 19.degree. of rotation of the cam, and the remaining periphery of the cam includes a follower return portion and a dwell portion. When the cam follower engages the toe portion of the cam, the shaft is oscillated rapidly in one direction which causes the lug strap to slap against the picker stick and swing the picker stick inwardly and move the upper end of the picker stick through the check strap while throwing the shuttle from one end of the lay to the other. Ordinarily, the movement of the cam follower system and the picker sticks to throw the shuttle across the lay occurs while the lay is moving back and forth of the loom. The shaking, banging, slapping and other related movements of the shuttle drive mechanism have not only created substantial noise directly, but have caused sound producing vibrations to occur in many of the parts including the picker stick so that a noise level which is detrimental to humans has been created within weaving rooms.
Since there is a cam operated picker stick at each end of the lay, only one picker stick is operated for each beat-up motion of the lay and, therefore, the cam drive mechanisms are operated at half the speed of the lay drive mechanism. Although the cam and follower system is relatively slow in terms of pure speed, it is normally regarded as a high-speed cam system because of the mass of the cam and follower system, picker stick and drive mechanism and the inertia forces which are involved. Also the power consumption has been large due to the size of the power plant necessary to overcome the various forces as well as to drive the loom at a speed of approximately 178 picks per minute.
In missile type looms, the weft thread is connected to a relatively small missile and such missile is thrown from one end of the lay to the other through the shed of the warp threads. In order to throw the missile, a lever is fixed at one end to a torsion bar and the other end of such lever is swingably connected to a connecting link which in turn is connected to a pick shoe which engages the missile. The lever normally is engaged by a cam which applies a torque to the torsion bar and moves the pick shoe to a cocked position. When the lever is released, the torsion bar causes the pick shoe to throw the missile to the opposite end of the lay. Normally in missile type looms, a plurality of missiles are provided and each missile has a clamping mechanism for engaging the weft thread. When the weft thread has been attached to the missile, such missile is placed in front of the pick shoe after the pick shoe has been cocked and the missile is thrown from one side of the lay to the other. When the missile has traversed the lay, the clamping mechanism is released and the missile is returned to the first side of the loom through a return channel which is spaced from the lay. In this type of loom, the weft thread is placed in the shed from one side only and is not moved back and forth as in the fly shuttle loom.
Some efforts have been made to eliminate the cam drive mechanism of fly shuttle and missile type looms by providing linkages of various kinds for driving the shuttle or missile of the weft thread carrying mechanism from one end of the lay to the other while the lay is immobile; however, an extended dwell period normally is required to permit the lay to be advanced and retracted for the beat-up operation, as well as to permit time for the harnesses carrying the heddles to be operated so that the desired warp threads can be shifted. In most of the prior art structures, it has been difficult to provide a dwell period in excess of approximately 180.degree. of rotation of the drive mechanism.
Some examples of prior art structures which include linkages are the patents to Schwabe U.S. Pat. No. 540,878; Kellogg et al U.S. Pat. No. 2,066,532; and Dyer U.S. Pat. No. 3,270,779.